The present invention relates to a synchronous motor comprising a rotor with permanent magnet and a stator with a homopolar field having a winding connected to an AC voltage source.
This type of motor is a small low cost power motor used more particularly in the home electric appliance field.
Such motor has the drawback of not having a predetermined direction of rotation and of starting either in one direction or in the other, in a random fashion, unless special precautions are taken.
For the majority of applications of such motors, such uncertainty concerning the direction of rotation is not tolerable. One prior art solution is to provide, on such a motor, a mechanical device, e.g. a pawl, for imposing a given direction of rotation on the rotor.
However, the use of a pawn in this manner limits the use of the motor for applications in which, once installed, it has to rotate in one direction only. Now, in numerous applications, it is convenient to be able to drive a member at will either in one direction or in the other, this choice being made through an electric control signal. In such applications, the known synchronous motor, with its pawl, is not usable.